I have a website www.abc.com on Server-A (shared server). I have IPB (Invision) forum installed in the website. Since the server is shared, I am unable to send bulk mails to my registered users. (The shared server is not allowing it because it affects the server performance.)

Now I have purchansed a dedicated server (Server-B). But I don't want to move my website www.abc.com to this new server. I just want to use this dedicated server for sending mails.

So I used the SMTP settings of this new server in my website's forum software (the website is still located on shared server)

But it gives error message - "503 This server does not support authorisation" and the mails are not being sent.

I think the SMTP request from my website (on shared server) is trying to authenticate against the dedicated server's SMTP server, but is failing as the dedicated server is not configured to accept connections from other servers.

So I need to configure the SMTP server on Server-B (dedicated server) to accept connections from the IP address/domain of my shared server.

My Questions:
1) How to change the Exim configuration (in the Exim Configuration Editor) to accept SMTP connections from my website located on shared server.

2) Is there any risk in doing that ? (like spammers using my SMTP server to send their mails)